The present invention relates to measuring devices and more particularly to devices for measuring the alignment and misalignment of interconnected pipes, shafts, and their joints.
Prior art devices designed to measure alignment of flange coupled pipes and shafts have commonly employed arcuate members configured so they may be secured in close-fitting relation to the pipes or shafts immediately adjacent to the joint whose alignment is to be ascertained. The arcuate members are accurately positioned so their alignment reflects the alignment of the pipe or shaft to which they are affixed. These members then serve as a base structure for instruments which project across the joint and measure the position and alignment of the flanges and the opposing pipe. Unfortunately, these devices are bulky and costly besides being difficult and time consuming to use.
Simplified techniques have been required to measure the alignment of rubber expansion joints in water pipes comprised of a central section housing a flanged elastic expansion segment secured to the main pipes by a split flange arrangement. It is often necessary for many such joints to be checked in short periods of time. Therefore, to affect a rapid procedure for checking such joints, pairs of opposing holes have been drilled on the pipe flanges between which diagonal and axial distances can be quickly measured to check flange and pipe alignment. At best, this method alerts the technician to possible changes in alignment since previous readings were made. It does not provide the mathematics necessary to translate the readings into absolute values of misalignment, and, even if it did, it would be extremely difficult to use because of the accuracy needed in placing holes and making diagonal readings. Consequently, no simple, accurate, and rapid technique currently exists for measuring the alignment of pipes, shafts, and their joints as is especially needed for use in determining the alignment of water pipe expansion joints on ships.